The moisture content of grains and like material has a significant impact on the market value of the grain. If grains have too high of moisture content they will sell for less than those in an appropriate moisture range. Therefore, an accurate and precise means of testing moisture content in grain will help farmers monitor their crops. With the aid of monitoring, farmers may dry their grain until the preferred moisture content is achieved. This will minimize energy input while increasing grain value.
There are many grain moisture sensing devices found in the patent literature. Greenwood et al. Canadian patent 510356, issued Feb. 22, 1955, which corresponds to U.S. Pat. No. 2,693,575 issued December 1951, describes a device allowing a relatively unskilled operator to measure moisture content of a sample rapidly by measuring its dielectric properties. This device has proven to be very successful in the grain industry and has become a preferred instrument of many organizations in that industry, for example the Canadian Grain Commission. Thus it acts as a standard in many situations and remains therefore a widely used and effective tool for measuring grain moisture. This remains so despite its using old technology, so that it has not been superseded by recent developments using technology which is potentially much more accurate and effective. The device is rugged and of basically simple components such as manually adjustable capacitors.
Unfortunately, the manufacture and maintenance of this device has become difficult due to the age of the technology. The device has two vacuum tube oscillators with an operating frequency of several MHz, requiring the use of specially wound inductance coils. Manufacturers have discontinued or are discontinuing production of those components. Hence, it is becoming increasingly more difficult to acquire them for either manufacture or repair. It is clear that the device is in need of an update to use components that are currently readily available.
In addition to the concerns over manufacture and repair, there are certain deficiencies in the original device. For example, the length of time for temperature stabilization of the electronics and uncertainties in setting a calibrated standard capacitor using an analogue milliammeter. On the latter point, with the prior art meter, the needle of the ammeter has only positive readings. The capacitor is adjusted to achieve the desired zero current state. The dial reading is positive regardless of whether the capacitance is too high or too low. In adjustment, the dial needle moves to one end of the dial as the measured current output approaches zero. On passing through the point of zero current, the reading begins to rise again, as the needle moves back to the opposite end of the dial. This makes it very difficult to determine the exact point at which the reading is at a minimum and the capacitor is adjusted correctly to provide an accurate reading.
One clearly desirable approach would be to manufacture a new device of a new design using modern technology and modern components and a number of attempts to do this have been made although none have had significant success primarily in view of the fact that the above device remains a standard and thus is not easily displaced.
Another approach is to modify the construction of the existing equipment so that the basic components of the housing, the cell for receiving the sample, its mounting on the housing and the manually variable capacitors remain unchanged but the electronic components are modified for improved operation.